Site Search
Print Page Setup Profile Login
You have 4 items in your shopping cart
Section Image

Tyre legalities

Submitted: Saturday, Nov 10, 2001 at 00:00

Grant

We are wanting to change over to Cooper S/T's on our Jack but they only come as a 245/75R16 and we are running at present 245/70R16 Cooper H/T's. What are the legalities on running say 75's on the front and 70's on the rear until the 70's are worn out? My gut feeling is it would be illegal but someone may know otherwise. Look forward to any replies.
Grant.............happy trails.
Advertisement
ThreadID: 542 Replies: 2
Views: 565 FollowUps: 2
This Thread has been Archived
Thread Summary
Thread Watch Back To Forum Alert Moderator FAQ
AnswerID: 1395   Submitted: Sunday, Nov 11, 2001 at 00:00

Mark replied:

Grant,

Not sure about the legalities but it would probably not do your transmission much good as the front wheels would be turning at a different rate than the rears. As an example BFG 245/70 16 complete 705 revolutions per mile whereas the 245/75 16 completes 680 revolutions per mile. With the center diff locked this would give problems such as transmission wind-up.

Mark
Reply 1 of 2
AnswerID: 1411   Submitted: Monday, Nov 12, 2001 at 00:00

Col replied:

Grant,

Dont mix your tyre sizes! I am looking seriously at the Cooper S/T's. A couple of other members of the Jackaroo Club have put them on. The size they went with was 255/70. I believe that also kept them legal in regard to the load rating, with a very minor reduction in speedo accuracy.

Regards,

Col
Reply 2 of 2
FollowupID: 435   Submitted: Tuesday, Nov 13, 2001 at 00:00

Grant posted:

Thanks guys, I hadn't considered the trans wind-up but we never run locked on firm surfaces so never thought about it. It's a good point though, coz one day we just might. Theres a light truck type and a P-metric type S/T tyre in the Coopers catalogue and it may be a difference in the number of ply's. Anyone know what P-metric is? The P-metric's are the only ones with a 70 type. Don't really want to go wider as more punctures may eventuate, would rather go thinner, but higher would be better for more underbody clearance. The speedo problem I would have to put up with. I will have to go to the nearest Coopers man and trust what he tells me. Thanks again.
FollowUp 1 of 2
FollowupID: 437   Submitted: Wednesday, Nov 14, 2001 at 00:00

Mark posted:

Grant,
P-metric: This is the United States version of a metric sizing system established in 1976. P-Metric passenger car tire sizes begin with "P", which simply means "Passenger"
Also I priced a set of Cooper ST's recently for my Disco and the size was 235/70 R16 maybe an option.

Mark
FollowUp 2 of 2

 Page Sponsors

ExplorOz ExplorOz
Become a Member of ExplorOz; buy or sell in Trader; buy Maps, Books, DVDs, camping accessories, and ExplorOz wheel covers, shirts, hats and stubby holders from the ExplorOz Shop; and book Activities &Tours or buy someone a gift certificate from our Activities section. Become an ExplorOz Member for just $60 in your first year, and $40 when you renew.
PO BOX 967  HILLARYS, WA, 6923
Phone: (08) 9403 3737
More info | Website